Resin intake manifolds and manufacturing process thereof

ABSTRACT

A resin intake manifold includes a chamber section having an intake port which leads to a throttle body  91,  and a plurality of pipe sections  7  which connect interior of the chamber section to cylinders of a multi-cylinder internal combustion engine. The chamber section is made up of a plurality of port members  1  coupled together, each port member  1  including the pipe section  7  and a cylindrical section  6  whose external wall is connected to an end of the pipe section  7.

FIELD OF THE INVENTION

[0001] The present invention relates to a resin intake manifold fordistributing intake air through a throttle body of a multi-cylinderinternal combustion engine of an automobile, etc., or a gaseous mixtureof air and fuel into different cylinders of the multi-cylinder internalcombustion engine, and a manufacturing process of such a resin intakemanifold.

BACKGROUND OF THE INVENTION

[0002] The conventional choice of intake manifold is an intake manifoldmade of resin (resin intake manifold), chiefly due to its superiorproperties providing good insulation, lightweight, and more freedom interms of shape. The resin intake manifold includes a chamber sectionhaving an intake port which opens into a throttle body, and a pluralityof pipe sections which connect interior of the chamber section to therespective cylinder of a multi-cylinder internal combustion engine. Theconfiguration of the resin intake manifold is generally complex and itsmanufacturing process generally involves splitting the resin intakemanifold into a plurality of half-parts and later joining them in apost-process. In this case, in order to reduce the number of divisionsof the resin intake manifold, a slide mechanism which can form aplurality of pipe sections at once has been known.

[0003] {circle over (1)} Japanese Unexamined Patent Publication No.166875/1995 (Tokukaihei 7-166875) (published date: Jun. 27, 1995) and{circle over (2)} Japanese Unexamined Patent Publication No. 231760/1998(Tokukaihei 10-231760) (published date: Sep. 2, 1998) disclose a resinintake manifold which has an opening, leading to a throttle body, at oneend of the chamber, and a plurality of pipes which are lined andintegrated with the chamber. Further, {circle over (3)} JapaneseUnexamined Patent Publication No. 196373/1998 (Tokukaihei 10-196373)(published date: Jul. 28, 1998) and {circle over (4)} JapaneseUnexamined Patent Publication No. 299591/1998 (Tokukaihei 10-299591)(published date: Nov. 10, 1998) disclose a resin intake manifold inwhich an opening leading to a throttle body is provided at a center ofthe chamber.

[0004] The resin intake manifolds of the foregoing publications {circleover (1)} through {circle over (4)} all have complex configurations,which force them to employ a manufacturing method using the slidemechanism which can create complex shapes with a small number ofdivisions.

[0005] However, with conventional methods using the slide mechanism, theresin intake manifold is formed by design, for example, from two orthree divided parts, and this requires a mold with a large manufacturingcost. Thus, when the number of intake manifolds manufactured is small,the manufacturing cost per product is increased. Further, manufacturingmethods using the slide mechanism require the pipes to be providedinside the chamber, which necessitates the use of an additional member,a partition wall, which is provided separately from a mold. Thepartition wall has a complex fitting structure, and causes the problemof flat areas in the inner wall surface of the pipe sections.

[0006] That is, resin intake manifolds generally have complexconfigurations, and to reduce the number of divisions, the slidemechanism has been used conventionally. However, manufacturing methodsusing the slide mechanism have problems that 1) it requires a large andexpensive mold and the manufacturing cost per product is increased whenthe number of products manufactured is small, 2) the partition wall usedto provide the pipe sections has a complex fitting structure, and 3)flat areas are formed in the inner wall surface of the pipe sections.

SUMMARY OF THE INVENTION

[0007] The present invention was made in view of the foregoing problems,and its object is to provide a resin intake manifold which can bemanufactured at low cost even when the number of products manufacturedis small, and a manufacturing process of such a resin intake manifold.

[0008] In the present invention, as the term is used herein, “resin”refers to those molding materials which can flow into a mold when meltedto become a molten material at a high temperature, and which becomesufficiently strong when solidify. Accordingly, the resin used in thepresent invention is not just limited to so-called polymer resins suchas plastic.

[0009] In order to achieve this object, a resin intake manifold of thepresent invention includes a chamber section with an intake port whichleads to a throttle body, and a plurality of pipe sections which connectinterior of the chamber section to respective cylinders of amulti-cylinder internal combustion engine, wherein: the chamber sectioncomprises a cylinder body which is made up of a plurality of portmembers coupled together, each of the plurality of port members having apipe section, and a cylindrical section whose external wall is connectedto one end of the pipe section.

[0010] The chamber section of the resin intake manifold of the presentinvention comprises a cylinder body which is made up of a plurality ofport members coupled together, each of the plurality of port membershaving a pipe section, and a cylindrical section whose external wall isconnected to one end of the pipe section. That is, the resin intakemanifold is divided into the port members which can be manufacturedusing a small mold of a low cost of production. As a result, less costis required for the mold, which allows the resin intake manifold to bemanufactured at low cost even when the number of products manufacturedis small.

[0011] The port members may be provided, for example, as a cast ofhalf-parts. That is, the port members can be provided without using theslide mechanism, and therefore do not require the use of the partitionwall having a complex fitting structure. This prevents areas of flatportions in the inner wall of the pipe section.

[0012] Further, by changing the number of port members of the chambersection, the product resin intake manifold can adapt to engines withvarious numbers of cylinders, provided that the cylinders of the enginehave substantially the same displacement. That is, the port member canbe used as a common member to manufacture a resin intake manifold whichcan adapt to engines with various numbers of cylinders. Thus,manufacturing cost of resin intake manifolds can be reduced.

[0013] In the present invention, “chamber section” refers to a hollowportion of a section whose external wall is connected to one end of thepipe section, and, for example, it is formed by coupling the cylindricalbody which is made up of the plurality of port members coupled together,a throttle body mounting pipe member, and a lid section which closes anend or both ends of the cylindrical body. Note that, the cylindricalbody may alternatively comprise the plurality of port members coupled toa cylindrical member which is provided with an intake port and insertedbetween any of the port members. The shape of the chamber section, whichis not particularly limited, is cylindrical, for example.

[0014] The resin intake manifold of the present invention may have anarrangement wherein the pipe section extends out of the chamber sectionto coil along the external wall of the chamber section, and at least aportion of the external wall of the pipe section on the side of theexternal wall of the chamber section is connected to the external wallof the chamber section.

[0015] With this arrangement, the air space of gap between the pipesection and the chamber section can be eliminated, thus making the resinintake manifold compact.

[0016] In addition, rigidity of the chamber section can be improved.Thus, for example, even when the chamber section is under high pressuredue to a backfire, etc., the pressure can be dispersed over the pipesection through the connected portion, thus preventing damage to thechamber section.

[0017] The resin intake manifold of the present invention may have anarrangement wherein an opening portion of the pipe section on the sideof the chamber section is in the form of a funnel.

[0018] With this arrangement, gas flows more smoothly from the chambersection to the pipe section, thus improving suction efficiency of thepipe section. According to this arrangement, the funnel is integrated asa portion of the pipe section when forming the port member. This makesthe inner wall of the opening portion in the form of a funnel smootherthan that of the funnel which is separately provided later to theopening end of the pipe section. As a result, gas flows more smoothlyfrom the chamber section to the pipe section, thereby further improvingsuction efficiency of the pipe section.

[0019] The resin intake manifold of the present invention may have anarrangement wherein: the chamber section comprises a cylindrical bodywhich is made up of the plurality of port members coupled to acylindrical member which is provided with an intake port and insertedbetween any of the port members, and the pipe section is curved to coilalong an external wall of the chamber section, and is bent toward theintake port.

[0020] With this arrangement, the resin intake manifold can be made morecompact while ensuring sufficient length for the pipe section.

[0021] The resin intake manifold of the present invention is preferablymanufactured by the steps of: forming the port member having the pipesection and the cylindrical section whose external wall is connected toone end of the pipe section; and forming the cylindrical body which ismade up of the plurality of port members coupled together.

[0022] This method allows the port members to be manufactured using asmall mold, thus manufacturing the resin intake manifold at lowproduction cost even when the number of products manufactured is small.

[0023] For a fuller understanding of the nature and advantages of theinvention, reference should be made to the ensuing detailed descriptiontaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024]FIG. 1 is a perspective view showing a resin intake manifold ofthe First Embodiment in a divided state.

[0025]FIG. 2 is a plan view showing an internal structure of the resinintake manifold of the First Embodiment.

[0026]FIG. 3 is a perspective view showing a structure of a port membermaking up the resin intake manifold of the First Embodiment.

[0027]FIG. 4(a) through FIG. 4(c) show a structure of the port membermaking up the resin intake manifold of the First Embodiment, in whichFIG. 4(a) is a side view; FIG. 4(b) is a cross sectional view takenalong the line A-A′; and FIG. 4(c) is a cross sectional view taken alongthe line B-A′.

[0028]FIG. 5 is a perspective view showing a structure of a port membermaking up a resin intake manifold of the Second Embodiment.

[0029]FIG. 6(a) through FIG. 6(c) show a structure of the port membermaking up the resin intake manifold of the Second Embodiment, in whichFIG. 6(a) is a side view; FIG. 6(b) is a cross sectional view takenalong the line D-D′; and FIG. 6(c) is a cross sectional view taken alongthe line E-D′.

[0030]FIG. 7 is a perspective view showing a structure of a port memberwith an opening portion in the form of a funnel.

[0031]FIG. 8 is a side view showing the port member with the openingportion in the form of a funnel.

[0032]FIG. 9 is a perspective view showing a structure of a resin intakemanifold used with a V-6 internal combustion engine according to theThird Embodiment.

[0033]FIG. 10 is a plan view showing a structure of a resin intakemanifold used with a V-6 internal combustion engine according to theThird Embodiment.

[0034]FIG. 11 is a plan view showing a structure of a resin intakemanifold used with an in-line internal combustion engine according tothe Fourth Embodiment.

[0035]FIG. 12 is a plan view showing a structure of a resin intakemanifold used with a V-8 internal combustion engine according to theFifth Embodiment.

DESCRIPTION OF THE EMBODIMENTS

[0036] The following will describe embodiments of the present inventionwith reference to FIG. 1 through 12.

First Embodiment

[0037] One embodiment of the present invention is described below withreference to FIG. 1 through FIG. 4. Note that, the present embodimentdescribes the case where a resin intake manifold of the presentinvention is applied to an in-line three-cylinder internal combustionengine.

[0038] As shown in FIG. 1 and FIG. 2, the resin intake manifold of thepresent invention includes port members 1 a, 1 b, 1 c, a throttle bodymounting pipe member (cylindrical body, chamber section) 2, a lid member(chamber section) 3, and a cylinder head mounting board member 4.

[0039] The port members 1 a through 1 c of the resin intake manifold ofthe present invention all have the same configuration, and thus the portmembers 1 a through 1 c will be collectively referred to as a portmember(s) 1 unless distinguished otherwise. One end of the throttle bodymounting pipe member 2 makes up an intake port 5 which leads to athrottle body 91, and the other end makes up a joint face joined with acylindrical section (cylindrical body, chamber section) 6 of the portmember 1. The cylinder head mounting board member 4 serves to connectopening ends of pipe sections 7 of the port members 1 to cylinders 92 a,92 b, 92 c of the in-line three-cylinder internal combustion engine.Note that, the cylinders 92 a, 92 b, 92 c will be collectively referredto as a cylinder 92 unless distinguished otherwise. The throttle bodymounting pipe member 2 is joined with one end of the cylindrical bodywhich is composed by joining cylindrical sections 6 of the port members1 to one another, and the other end of the cylindrical body is joinedwith the lid member 3, so as to form the chamber section of the resinintake manifold.

[0040] The port member 1 comprises, as shown in FIG. 3, a pipe section7, and the cylindrical section 6 with its external wall integrated withone opening end of the pipe section 7. The pipe section 7 is curvedalong the external wall of the cylindrical section 6. The other openingend of the pipe section 7 leads to the cylinder 92 via the cylinder headmounting board member 4.

[0041] Between the external wall of the pipe section 7 and that of thecylindrical section 6, there exists a gap (air space), as shown in FIG.4(a). The port member 1 is formed by joining divided half-parts of theport member 1 along the line C-C′ as shown in FIG. 4(b) and FIG. 4(c).Methods of joining the half-parts are not particularly limited, and thepresent embodiment employs a method using molten resin.

[0042] In this method using molten resin, the joint face of eachhalf-part is provided with a groove so that it combines with the otherto form a molten resin groove when the half-parts are joined. The jointfaces of the half-parts are then joined by flowing molten resin in themolten resin groove while the joint faces of the half-parts are mated.In the present embodiment, the port member 1 is formed by joining thedivided half-parts along the line C-C′ by flowing molten resin in themolten resin groove 9.

[0043] Specific examples of the method using molten resin include theDSI (Die Slide Injection) method, and a DRI (Die Rotary Injection)method.

[0044] The DSI method is disclosed in Japanese Unexamined PatentPublication No. 87315/1987 (Tokukaisho 62-87315) (published date: Apr.21, 1987) [Japanese Examined Patent Publication No. 38377/1990(Tokukouhei 2-38377) (published date: Aug. 30, 1990)]. Specifically, themethod employs a pair of molds of male and female patterns for castinghalf-parts of a hollow cast, wherein the male and female patterns of onemold face the opposite patterns, namely, the female and male patterns,of the other mold. The half-parts are casted by injecting molten resininto a pair of cavities between opposing male and female patterns. Then,one of the mold is slid so that the half-parts remaining in the femalepatterns of the respective molds are mated with each other. The pairs ofhalf-parts so mated are then joined each other by injecting molten resinaround the periphery of the mating faces. The end product of theseprocedures is the hollow cast.

[0045] The DRI method, which is a process for manufacturing a hollowbody, is disclosed in Japanese Unexamined Patent Publication No.91914/1992 (Tokukaihei 4-91914) (published date: Mar. 25, 1992)[Japanese Examined Patent Publication No. 4830/1995 (Tokukouhei 7-4830)(published date: Jan. 25, 1995)]. Specifically, it is the method ofmanufacturing a hollow body by the steps of molding one half of a hollowbody; molding the other half of the hollow body; and mating the twohalf-parts. This method employs a pair of molds combined to open orclose with respect to each other, one capable of rotating with respectto the other, and each having at least one male and two female patternson its molding surface. In the first step of injection molding (firstmolding step), the first half-part is molded in a male-female cavity,the second half-part is molded in a female-male cavity, and a whole partis molded in a female-female cavity by mating the first half-part andthe second half-part which were molded in the previous sequence. Themolds are then separated from each other (mold releasing step). In thenext step (forward or reverse rotation step), one of the molds isrotated relative to the other by a predetermined angle in a forwarddirection or reverse direction, so as to mate the male pattern of one ofthe molds with either female pattern of the other mold, and the femalepatterns of the two molds with each other. In the next step (secondmolding step), the sequence of the first molding step is repeated sothat the first half-part is molded in a male-female cavity, the secondhalf-part is molded in a female-male cavity, and a whole part is moldedin a female-female cavity by mating the first half-part and the secondhalf-part which were molded in the first molding step. The hollow bodyis manufactured by repeating these sequences.

[0046] Another example of the methods of joining the half-parts, otherthan the method using molten resin, is a vibration fusing method bywhich the mating faces are joined by fusion by the heat of friction.Note that, when the vibration fusing method is adopted to join thehalf-parts, no grooves will be required on the mating faces of thehalf-parts to provide the molten resin groove 9.

[0047] Further, the mating faces of the cylindrical section 6 of theport member 1 has a raised portion 10 on one end and a recessed portion11 on the other end in the form of a continuous ring along a centralportion of these faces. The raised portion 10 and the recessed portion11 are fitted to each other when the port members 1 are joined at themating faces.

[0048] The method of joining the port member 1, the throttle bodymounting pipe member 2, the lid member 3, and the cylinder head mountingboard member 4 is not particularly limited. Some of the Examples are:the vibration fusing method, a laser fusing method, a fastening methodusing an adhesive agent, a fastening method using a bolt, and afastening method using a nail.

[0049] As described, the chamber section of the resin intake manifold ofthe present invention is made up of the cylindrical body which iscomposed of a plurality of port members 1, each of which includes thepipe section 7 and the cylindrical section 6 whose external wall isintegrated with one end of the pipe section 7. That is, the resin intakemanifold of the present invention can be divided into port members 1,and therefore can be manufactured with the use of smaller molds thanthose used in the manufacturing method employing the slide mechanism. Asa result, less cost needs to be spent on the molds, and the resin intakemanifold can be manufactured at low cost even when the number ofproducts manufactured is small.

[0050] Further, because manufacture of the resin intake manifold doesnot employ the slide mechanism, there will be required no partition wallof the complex fitting structure, thus forming the pipe section 7 withsuperior suction efficiency with a substantially circular crosssectional area with no flat portions.

[0051] Further, resin intake manifolds with different numbers of pipesections 7 can be obtained by changing the number of port members 1 tobe joined. That is, provided that the cylinders of the engine havesubstantially the same displacement, the product resin intake manifoldcan adapt to engines with various numbers of cylinders. That is, theport member 1 can be used as a common member to manufacture resin intakemanifold which can adapt to engines with various numbers of cylinders.Therefore, manufacture of the resin intake manifold requires less cost.

[0052] The present embodiment described the resin intake manifold whichjoins three port members 1 to adapt to an in-line three-cylinderinternal combustion engine. However, the number of port members 1 is notjust limited to three and any number can be adopted.

[0053] Note that, the resin intake manifold of the present invention mayhave an arrangement including an intake pipe, leading to the throttlebody, which is provided at the center or one end of a cylindricalchamber, and a plurality of pipes which are integrated with a side wallof the chamber, wherein the resin intake manifold comprises a pluralityof port members coupled together, each port member configured tointegrate one end of the pipe with a cylindrical pipe of the chamber andto provide a port which is curved along the cylindrical pipe, the portmembers being coupled to a cylinder head mounting board member which isconnected to outlets of the respective ports of the port members, to alid member which closes an end of the chamber, and to a throttle bodymounting pipe member.

Second Embodiment

[0054] The following will describe another embodiment of the presentinvention with reference to FIG. 5 through FIG. 8.

[0055] As shown in FIG. 5 and FIG. 6, a pipe section 27 of a port member21 extends from a cylindrical section 26 (cylindrical body, chambersection) to coil along the external wall of the cylindrical section 26.Further, as shown in FIG. 6(a), the external wall of the pipe section 27on the side of the external wall of the cylindrical section 26 is atleast partially connected to the external wall of the cylindricalsection 26.

[0056] Thus, the arrangement of a resin intake manifold manufacturedwith the port member 21 is such that the pipe section 27 extends fromthe chamber section so as to coil along the external wall of the chambersection, and the external wall of the pipe section 27 on the side of theexternal wall of the chamber section is at least partially connected tothe external wall of the chamber section.

[0057] Because the external wall of the pipe section 27 is connected tothe external wall of the chamber section, there will be no air spacebetween the external wall of the cylindrical section 26 and that of thepipe section 27, thus making the resin intake manifold compact. Inaddition, rigidity (strength) of the chamber section can be improved.Thus, for example, even in case of an incidence such as a backfire whichexerts a high pressure on the chamber section, the pressure can bedispersed over the pipe section 27 through the connected portion of thechamber section and the pipe section 27. As a result, the chambersection will not be damaged.

[0058] The port member 21 is formed by joining the divided half-partsalong the line F-F′ as indicated in FIG. 6(a) and FIG. 6(c). The methodof joining the half-parts is not particularly limited, and the presentembodiment adopt the method using molten resin. Thus, the mating facesof the half-parts are provided with grooves in the form of a ring whichcombine to form a molten resin groove 29 which is filled with the moltenresin when the half-parts are joined. Note that, the mating faces of theport member 21 have a raised portion 30 and a recessed portion 31 aswith the port member 1.

[0059] As shown in FIG. 7 and FIG. 8, a port member 31 of the resinintake manifold of the present invention has a pipe section 37 whoseopening portion 40 on the side of a cylindrical section (cylindricalbody, chamber section) 36 is in the form of a funnel. With this openingportion 40 in the form of a funnel, the suction efficiency of the pipesection 37 can be improved.

[0060] Here, the port member 31, as with the port member 21, is formedby joining the half-parts of the port member 31 which are divided on aplane parallel to the mating faces of the cylindrical section 36, andtherefore the opening portion 40 can be integrally formed with the pipesection 37. This structure has an advantage over the structure in whichthe opening end of the pipe section 37 is additionally provided with afunnel, because the inner wall of the opening portion 40 in the form ofa funnel has a smoother surface. With this structure, gas flows into thepipe section 37 more smoothly, which in turn improves suction efficiencyof the pipe section 37 of the resin intake manifold.

Third Embodiment

[0061] The following will describe yet another embodiment of the presentinvention with reference to FIG. 9 and FIG. 10. The followingdescription of the present embodiment is based on the resin intakemanifold of the present invention used with a V-6 internal combustionengine.

[0062] As shown in FIG. 9 and FIG. 10, a resin intake manifold of thepresent embodiment includes the port member 1 (see FIG. 3), throttlebody mounting pipe member 2, lid member 3, and cylinder head mountingboard member 4. The pipe sections 7 are arranged so that their openingends to be connected to the cylinder head mounting board member 4alternately direct in opposite directions.

[0063] The resin intake manifold can be manufactured for use in aV-internal combustion engine by thus joining the port members 1 so thattheir pipe sections 7 alternately direct in opposite directions. Thatis, the port members 1 used for manufacture of the in-linethree-cylinder internal combustion engine (see FIG. 1, FIG. 2) can beused for the resin intake manifold of a V-internal combustion engine. Ineffect, by using the port members 1 as a common member, manufacturingcost of the resin intake manifold can be reduced.

[0064] The present embodiment described the resin intake manifold whichcomprises six port members 1 to adapt to a V-6 internal combustionengine. However, the number of port members 1 is not just limited tothree and any number can be adopted.

Fourth Embodiment

[0065] The following will describe still another embodiment of thepresent invention with reference to FIG. 11. Note that, the followingdescription of the present embodiment is based on the resin intakemanifold of the present invention used with an in-line 4-cylinderinternal combustion engine.

[0066] As shown in FIG. 11, the resin intake manifold of the presentinvention includes a port member 41, throttle body mounting pipe member(cylindrical body, chamber section, cylindrical member) 42, lid member(chamber section) 43, cylinder head mounting board member 44, and portmember 51. The chamber section of the resin intake manifold includes, atthe center in the lengthwise direction, an intake port 45 which leads toa throttle body (not shown).

[0067] The port member 41 is composed of a cylindrical section(cylindrical body, chamber section) 46, and a pipe section 47. The portmember 51 is composed of a cylindrical section (cylindrical body,chamber section) 56, and a pipe section 57. The pipe section 47 isshaped to coil along the external wall of the cylindrical section 46,and the pipe section 57 is shaped to coil along the external wall of thecylindrical section 56.

[0068] The chamber section of the resin intake manifold is structured toinclude the throttle body mounting pipe member 42 with the intake port45 between the port member 41 and the port member 51. That is, thechamber section makes up a cylindrical body joining the port member 41,the throttle body mounting pipe member 42, and the port member 51.

[0069] Thus, with this structure where the intake port 45 is provided atthe center in the lengthwise direction of the chamber section, therewill be a smaller difference of distances from the intake port to therespective pipe sections, compared with the structure where the intakeport is provided at an end in the lengthwise direction of the chambersection. Thus, the suction efficiency of the pipes can be made moreuniform. Further, because the pipe section 47 and the pipe section 57are bent in their way toward the intake port 45, the resin intakemanifold can be made compact.

Fifth Embodiment

[0070] The following will describe yet another embodiment of the presentinvention with reference to FIG. 12. Note that, the followingdescription of the present embodiment is based on the resin intakemanifold of the present invention used with a V-8 internal combustionengine.

[0071] As shown in FIG. 12, the resin intake manifold of the presentinvention includes a port member 41, port member 51, throttle bodymounting pipe member 42, lid member 43, and cylinder head mounting boardmember 44. The chamber section of the resin intake manifold is providedwith, at the center in the lengthwise direction, an intake port 45 whichleads to a throttle body (not shown). The port member 41 and the portmember 51 are arranged so that the opening ends of the pipe section 47and the pipe section 57 to be joined with the cylinder head mountingboard member 44 direct alternately in the opposite directions.

[0072] By thus disposing the pipe sections in different directions, theport members 41 and 51 of the in-line 4-cylinder internal combustionengine can be commonly used to manufacture the resin intake manifold fora V-8 internal combustion engine.

[0073] The intake port 45 of the resin intake manifold of the presentinvention is provided at the center in the lengthwise direction of thechamber section. Thus, compared with the structure where the intake portis provided at an end in the lengthwise direction of the chambersection, the suction efficiency of the pipes can be made more uniform.Further, because the pipe section 47 and the pipe section 57 are bent intheir way toward the intake port, the resin intake manifold can be madecompact.

[0074] It is preferable in a manufacturing process of the resin intakemanifold according to the present invention that, as described above, atleast two of the port members are adapted to have the sameconfiguration.

[0075] With this arrangement, at least two port members having the sameconfiguration can be manufactured in the same step. Thus, the number ofmanufacturing steps can be reduced to efficiently manufacture the portmembers. For example, when at least two port members having the sameconfiguration are to be formed using a mold, the same mold can be usedfor these port members. This, in effect, reduces the number of requiredmolds. Therefore, with the foregoing arrangement, intake manifolds canbe manufactured at low cost even when the number of productsmanufactured is small.

[0076] As described, the resin intake manifold according to the presentinvention includes an intake vessel which is provided with an intakeport leading to a throttle body, and a cylinder conduit conducting tocylinders of a multi-cylinder internal combustion engine, wherein theintake vessel comprises a plurality of port members each having thecylinder conduit.

[0077] In this arrangement, the intake manifold comprises a pipe whichbranches into a plurality of branch pipes which extend from the chambersection serving as a base of the branches. One of the branch pipesbecomes the intake port, while the others become pipes which conduct tocylinders of the multi-cylinder internal combustion engine.

[0078] Here, the intake vessel refers to the chamber section, or thecombination of the chamber section and the pipe section of the foregoingembodiments.

[0079] Further, the port members correspond to, for example, the portmembers 1 a, 1 b, 1 c as shown in FIG. 1. In the example of port members1 a, 1 b, 1 c, the cylinder conduit corresponds to the pipe section 7 asshown in FIG. 1. That is, in the foregoing example, the intake vesselcorrespond to the combination of the chamber section and the pipesection. Further, the intake port corresponds to the throttle bodymounting pipe member 2.

[0080] In the foregoing arrangement, the intake vessel of the resinintake manifold according to the present invention is made up of aplurality of port members. That is, according to this arrangement, theintake vessel does not comprise the intake vessel by itself, butcomprises the intake vessel by the combination of the port members.

[0081] Therefore, with this arrangement, the intake vessel can havedifferent numbers of branch pipes by changing the number of port membersused. Thus, the resin intake manifold according to the present inventioncan be manufactured to easily adapt to engines with various numbers ofcylinders by changing the number of port members used. Therefore, theresin intake manifold according to the present invention can bemanufactured at low cost, even when the number of products manufacturedis small, by using the foregoing port members.

[0082] Further, in the foregoing example, the port members 1 a, 1 b, 1 cas shown in FIG. 1 have the same configuration. However, the presentinvention is not just limited to this, and, for example, two or moreport members may have different configurations. Even so, the sameconfiguration as in the port members 1 a, 1 b, 1 c as shown in FIG. 1for example is preferable, because it allows the port members to bemanufactured in a single step, which reduces manufacturing cost.

[0083] Further, in the foregoing example, the port members 1 a, 1 b, 1 ceach have the pipe section 7 which corresponds to the cylinder conduit.However, the present invention is not just limited to this, and two ormore cylinder conduits may be provided for each port member. Even so,the port member is preferably provided with only single pipe section 7which corresponds to the cylinder conduit, as in the port members 1 a, 1b, 1 c as shown in FIG. 1, because this allows the port member to beused in engines with any number of cylinders. Further, the port memberwith a single cylinder conduit can be made more compact than the portmember with two or more cylinder conduits. This allows the use of, forexample, a smaller mold when it is used to form the port members,thereby reducing cost of the mold.

[0084] Further, for example, in the port members 1 a, 1 b, 1 c as shownin FIG. 1, the intake vessel is made up of the chamber section and thepipe section as described above, and the wall of the chamber section ofthe port member has a cylindrical wall. However, the present inventionis not just limited to this arrangement. That is, the wall of thechamber section of the port member should at least make up a portion ofthe chamber section. For example, the port member of the presentinvention may be adapted so that a portion of the wall of thecylindrical chamber section such as the cylindrical section 6 as shownin FIG. 1 is divided into two parts on a place including the axis of thecylinder, and a member analogous to the cylinder conduit is attached onthe external wall of the divided part, and finally a portion of the wallwhere this member was attached is opened. In short, the wall of thechamber section of the port member does not necessarily need to have thecylindrical wall. However, the port member with the chamber sectionpartially having a cylindrical wall is preferable because it requiresless coupling sites compared with the port member which does not havethe cylindrical wall. Thus, in addition to reducing manufacturing cost,the strength of the intake manifold can be improved.

[0085] Further, for example, in the port members 1 a, 1 b, 1 c as shownin FIG. 1, the pipe section 7 which corresponds to the cylinder conduitis included in the port member in its entirety. However, the presentinvention is not just limited to this arrangement. For example, the portmember of the resin intake manifold according to the present inventionmay have an arrangement which is essentially the same as that of theport members 1 a, 1 b, 1 c as shown in FIG. 1, but does not include thepipe section 7. In this case, the intake vessel corresponds to only thechamber section, rather than the combination of the chamber section andthe pipe section. In such an arrangement, the pipe section 7 isadditionally provided to be joined to the port member of thisarrangement. Despite these, the arrangement where the port memberentirely includes the pipe section 7 which corresponds to the cylinderconduit, for example, as in the port members 1 a, 1 b, 1 c as shown inFIG. 1 is preferable because it requires less coupling sites and lesscost.

[0086] As described, the resin intake manifold according to the presentinvention having the foregoing arrangement may be adapted so that atleast two of the port members have the same configuration.

[0087] According to this arrangement, as in the foregoing manufacturingprocess, at least two port members having the same configuration can bemanufactured in the same step. Thus, the number of manufacturing stepscan be reduced to efficiently manufacture the port members. For example,when at least two port members having the same configuration are to beformed using a mold, the same mold can be used for these port members.This, in effect, reduces the number of required molds.

[0088] The resin intake manifold according to the present inventionhaving the foregoing arrangement may be adapted so that portions of theport members where they are coupled to each other have a fittingstructure at least partially.

[0089] An example of such a fitting structure is the raised portion 10and the recessed portion 11 of the port member 1 as shown in FIG. 4(b)and FIG. 4(c).

[0090] In the foregoing arrangement, by the fitting structure, thecoupling strength of the port members can be improved.

[0091] The resin intake manifold according to the present inventionhaving the foregoing arrangement may be adapted so that the cylindricalconduit is in the form of a pipe which extends outward from the intakevessel.

[0092] According to this arrangement, an example of the cylinder conduitin the form of a pipe is the pipe section 7 as shown in FIG. 1. Withthis arrangement, since the port member is formed including the pipesection, it is not required to additionally join the pipe section withthe port member, which would be required when the port member is formedwithout the pipe section.

[0093] The resin intake manifold according to the present inventionhaving the foregoing arrangement may be adapted so that the cylinderconduit of the port members adjacent to each other extends alternatelyin opposite directions.

[0094] This arrangement enables manufacture of intake manifolds forV-engines. That is, the resin intake manifold according to the presentinvention, with the foregoing port members, can be used to manufactureintake manifolds for V-engines. That is, the port members can be sharedto reduce manufacturing cost.

[0095] The resin intake manifold according to the present inventionhaving the foregoing arrangement may be adapted so that the externalwall of the cylinder conduit is connected to the external wall of theintake vessel.

[0096] An example of an intake manifold having such an arrangement isthe intake manifold with the arrangement as shown in FIG. 6(a).

[0097] According to this arrangement, since the cylinder conduit isconnected to the external wall of the intake vessel, the intake manifoldcan be made compact. Further, since the cylinder conduit is connected tothe intake vessel, the strength of the intake manifold can be improved.

[0098] The resin intake manifold according to the present inventionhaving the foregoing arrangement may be adapted so that an inner wall ofthe intake vessel where the cylinder conduit extends into the intakevessel is in the form of a funnel.

[0099] An example of an intake manifold having such an arrangement isthe intake manifold as shown in FIG. 7 and FIG. 8. In the example ofFIG. 7 and FIG. 8, the cylinder conduit corresponds to the pipe section37. Further, in the example of FIG. 7 and FIG. 8, the intake vesselcorresponds to the cylindrical section 36 and the pipe section 37.Further, in the example of FIG. 7 and FIG. 8, the portion where thecylinder conduit extends into the intake vessel corresponds to theopening portion 40. Further, in this example, the opening portion 40 isin the form of a funnel.

[0100] With the arrangement wherein an inner wall of the intake vesselwhere the cylinder conduit extends into the intake vessel is in the formof a funnel, suction efficiency of the intake manifold can be improved.

[0101] The resin intake manifold according to the present inventionhaving the foregoing arrangement may be adapted so that the cylinderconduit is curved along an external wall of the intake vessel, and isbent toward the intake port with respect to an end of the cylinderconduit conducting to the cylinders of the multicylinder internalcombustion engine.

[0102] An example of an intake manifold having such a arrangement is theintake manifold as shown in FIG. 12. In the example of FIG. 12, thecylinder conduit independently corresponds to the pipe section 47 andthe pipe section 57. Further, in the example of FIG. 12, the intake portindependently corresponds to the throttle body mounting pipe member 42and the intake port 45.

[0103] According to the foregoing arrangement, the pipe section 47 andpipe section 57 corresponding to the cylinder conduit are curved alongthe external wall of the intake vessel. Further, the pipe section 47 andpipe section 57 corresponding to the cylinder conduit are bent towardthe intake port 45 of the throttle body mounting pipe member 42 whichcorresponds to the intake port, with respect to an end of the pipesection 47 and pipe section 57 conducting to the cylinders of themulti-cylinder internal combustion engine.

[0104] This arrangement is advantageous because it can make the intakemanifold compact while ensuring sufficient length for the cylinderconduit.

[0105] Note that, the foregoing embodiments described the case where theport members were used and combined as the basic unit to form the intakevessel or the intake manifold. However, the present invention is notjust limited to this arrangement. That is, for example, as describedwith reference to FIG. 4(b) and FIG. 4(c), the half-parts of the portmembers may be used as the basic unit. In other words, in the example ofFIG. 4(b) and FIG. 4(c), for example, the raised portion 10 and therecessed portion 11 of the half-parts may be mated to form whole parts,which are later combined to form the intake vessel. That is, the resinintake manifold according to the present invention includes all thoseintake manifolds which have at least two of the foregoing basic unitsanalogous to the port member of the present invention, regardless of theconfiguration of the smallest basic units which are combined, or theprocedure of combining these basic units.

[0106] The invention being thus described, it will be obvious that thesame way may be varied in many ways. Such variations are not to beregarded as a departure from the spirit and scope of the invention, andall such modifications as would be obvious to one skilled in the art areintended to be included within the scope of the following claims.

What is claimed is:
 1. A resin intake manifold having a chamber sectionwith an intake port which leads to a throttle body, and a plurality ofpipe sections which connect interior of the chamber section torespective cylinders of a multi-cylinder internal combustion engine,wherein: said chamber section comprises a cylinder body which is made upof a plurality of port members coupled together, each of the pluralityof port members having a pipe section, and a cylindrical section whoseexternal wall is connected to one end of the pipe section.
 2. The resinintake manifold as set forth in claim 1, wherein: the pipe sectionextends from the chamber section so as to coil along an external wall ofthe chamber section, and an external wall of the pipe section on theside of the external wall of the chamber section is at least partiallyconnected to the external wall of the chamber section.
 3. The resinintake manifold as set forth in claim 1, wherein an opening portion ofthe pipe section which opens into the chamber section is in the form ofa funnel.
 4. The resin intake manifold as set forth in claim 1, wherein:the chamber section comprises a cylindrical body which is made up of theplurality of port members coupled to a cylindrical member which isprovided with an intake port and inserted between any of the portmembers, and the pipe section is curved to coil along an external wallof the chamber section, and is bent toward the intake port.
 5. A processfor manufacturing a resin intake manifold having a chamber section withan intake port which leads to a throttle body, and a plurality of pipesections which connect interior of the chamber section to respectivecylinders of a multi-cylinder internal combustion engine, wherein saidchamber section comprises a cylinder body which is made up of aplurality of port members coupled together, each of the plurality ofport members having a pipe section, and a cylindrical section whoseexternal wall is connected to one end of the pipe section, said processcomprising the steps of: forming the port member having the pipe sectionand the cylindrical section whose external wall is connected to one endof the pipe section; and forming the cylindrical body which is made upof the plurality of port members coupled together.
 6. The process as setforth in claim 5, wherein at least two of the port members have the sameconfiguration.
 7. A resin intake manifold having an intake vessel whichis provided with an intake port leading to a throttle body, and acylinder conduit conducting to cylinders of a multi-cylinder internalcombustion engine, wherein the intake vessel comprises a plurality ofport members each having the cylinder conduit.
 8. The resin intakemanifold as set forth in claim 7, wherein at least two of the portmembers have the same configuration.
 9. The resin intake manifold as setforth in claim 7, wherein portions of the port members where they arecoupled to each other at least partially have a fitting structure. 10.The resin intake manifold as set forth in claim 7, wherein the cylinderconduit is in the form of a pipe which extends outward from the intakevessel.
 11. The resin intake manifold as set forth in claim 10, whereinthe cylinder conduit of the port members adjacent to each other extendsalternately in opposite directions.
 12. The resin intake manifold as setforth in claim 10, wherein an external wall of the cylinder conduit isconnected to an external wall of the intake vessel.
 13. The resin intakemanifold as set forth in claim 10, wherein an inner wall of the intakevessel where the cylinder conduit extends into the intake vessel is inthe form of a funnel.
 14. The resin intake manifold as set forth inclaim 10, wherein the cylinder conduit is curved along an external wallof the intake vessel, and is bent toward the intake port with respect toan end of the cylinder conduit conducting to the cylinders of themulti-cylinder internal combustion engine.